If $arg(z) < 0$,then $arg(-z) - arg(z)$ is equal to

An inductor coil carries a steady-state current of $2.0 \, A$ when connected across an ideal battery of $emf \ 4.0 \, V$. If its inductance is $1.0 \, H$,find the time constant of the circuit in $sec$.

In which of the following molecules/ions are all the bonds not equal?

The primary winding of a transformer has $100$ turns and its secondary winding has $200$ turns. The primary is connected to an $AC$ supply of $120$ $V$ and the current flowing in it is $10$ $A$. The voltage and the current in the secondary are:

The average marks of $10$ students in a class was $60$ with a standard deviation of $4$,while the average marks of another $10$ students was $40$ with a standard deviation of $6$. If all the $20$ students are taken together,their standard deviation will be:

If $A = \{2, 4, 5\}$ and $B = \{7, 8, 9\}$,then $n(A \times B)$ is equal to: